Some muscular manifestations of hypothyroidism.

Although it has been recognized for many years that symptoms and signs indicating disordered function of the voluntary musculature may be prominent in patients with myxoedema, the muscular manifestations of hypothyroidism have received comparatively little attention in the British literature. Recent reviews have, however, been given by Thomasen (1948), Piaggio Blancho and Malosetti (1950), Millikan and Haines (1953), Herbeuval, Cuny, and Larcan (1956), Dubansky, Svoboda, and Wiedermann (1957), and Perugini and Prati (1957). Kocher (1892) reported that patients with sporadic cretinism or myxoedema often showed bulky musculature, diminished muscular power, and sluggish movement with or without "tetany". Hoffmann (1897) later described features suggestive of myotonia in a patient who had undergone thyroidectomy several times; he pointed out that in this case there was a striking delay in muscular relaxation, reminiscent of that which occurs in myotonia congenita (Thomsen's disease). Since these early descriptions the syndrome of generalized muscular hypertrophy with sluggishness of muscular contraction and relaxation, which occurs in myxoedematous adults, has been referred to as "Hoffmann's syndrome". A similar disorder seen in cretinous infants is generally called the "DebreSemelaigne syndrome". Probably this disorder accounts for many cases of so-called acquired myotonia or myotonia acquisita (Talma, 1892). In fact, however, the abnormality of muscle function which results from hypothyroidism must be distinguished from true myotonia, as the overall slowness of muscular activity affects muscular contraction as well as relaxation and the typical electrical after-discharge of myotonia is not seen. Hence the term "pseudomyotonia" is a more appropriate description for the myxoedematous phenomenon. Whereas it is not difficult in patients with florid myxoedema to appreciate that slowness of movement and stiffness of the voluntary muscles may be attributable to the thyroid disease, particularly when there is also marked muscular hypertrophy, we have been impressed by the fact that the muscular symptoms may not always follow the accepted form and may be the presenting feature in patients in whom hypothyroidism is otherwise clinically unobtrusive. We report below three cases in which diagnosis presented considerable difficulty but nevertheless the response to treatment was rapid and sustained.